Geeks’ Corner: The Miracle of Xanthan Gum

I just had to pull the Joe Pastry train off to the side tracks for a moment to extoll the virtues of a truly amazing ingredient: xanthan gum. Oh sure, people demonize it, but usually without bothering to find out what it really is or does. The fact that it sounds “science-y” is enough to elicit derision from certain purist foodie types. They know not of what they speak.

Xanthan gum was invented in the heyday of corn sugar fermentation research, the 1960’s. At the time, folks in the USDA labs were looking for a thickener that was more versatile and efficient than corn starch and easier to produce than guar gum. One day, they allowed a culture of a bacterium by the name of Xanthomonas campestris to feed on a solution of corn-derived glucose. What resulted was a slimy, colorless substance that turned out to be one of the most broadly useful food ingredients currently known to man. For it turns out that in the process of digesting the glucose, the bacteria rearranged the individual sugars into longer-chain sugars (polysaccharides) with truly amazing properties.

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May I add…

…that a couple of recent baking projects have become sleeper hits among my family, friends and neighbors. The first is the vanilla slice, which is now the particular obsession of little Joan Pastry. The second is bee sting cake, which has become such a neighborhood favorite that I can barely keep up with the requests. I shall continue to work on perfecting the vanilla slice, but those of you who have yet to try bee sting cake, I heartily recommend it. Your friends and family will thank you.

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Air

Please excuse the lack of photo. Air is a thickener we commonly take for granted, but bubbles slow the flow of water as well as any other type of thickener. Where would our egg white foams be without it? Of course the trouble with bubble thickening is that bubbles tend to pop. That’s largely a […]

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Fat

Melted fats or liquid oils make very effective thickeners in watery mediums. Oil and water won’t dissolve in each other, so when you combine them the result is a mutual disaffection that runs all the way down to the molecular level. Cooks can force the two to mix by a liberal application of the whip, which has the effect of breaking up large blobs of fat into many smaller ones. The thing is that no matter how small the blobs get they’re still many times larger than water molecules, and so do a very effective job at slowing down their flow.

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Cornstarch (Corn Flour)

Cornstarch is, obviously, a starch thickener which means it thickens much the same way wheat flour does: with tangles of long-chain sugars that slow down the flow of the water around them. However there are several important differences between wheat flour and corn starch. One of those is particle size. Cornstarch is milled much finer than wheat flour, which means when those particles come in contact with hot water, they begin to shed starch molecules much faster. So cornstarch thickening happens faster than wheat flour thickening, but then also “un-thickens” that much faster.

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Little Help: Whipped Cream Substitute

Reader Elizabeth has an interesting challenge. Her husband has a severe milk protein allergy, yet he loves baked goods. She’s in search of a non-dairy substitute for whipped cream, but here’s the kicker: it can’t have coconut milk in it either. Anyone out there have any ideas?

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Wheat Flour

Plain wheat flour is a go-to thickener in the kitchen, especially where sauces care concerned. In combination with butter or oil it becomes a roux, which is the basis of classic béchamel. White flour, most bakers know, is the ground endosperm of a wheat berry, the endosperm being the energy storehouse of the seed. Moisten the seed and enzymes in the endosperm go about breaking down the long chain starches that are stored there into simple sugars. These sugars fuel the sprout (contained in the germ) as it grows.

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Gelatin

Gelatin is a protein, one that’s derived from a very interesting material called collagen. If you were to think of an animal’s body like a machine, where the bones and joints are the moving parts and the muscles are the motors, collagen is the rope and cabling that connects it all together. In fact collagen molecules are constructed very much like rope: three long protein molecules (individually known as gelatins) woven around each other to form a tight triple-helix. They’re very strong, the perfect material for making things like tendons and other so-called “connective” tissues.

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A Thickener Primer

Most of the time, when we’re talking about thickening in the kitchen, we mean the thickening of watery substances: broth, juice, milk, thin syrups, that sort of thing. Thickening is necessary if we want those substances to have much texture other than…watery. The obvious question here is: why can’t water itself have a more interesting texture? Does it have to be so, well, watery? And what makes it that way? The answer is that water flows because its molecules are so incredibly small. They’re made up of just three atoms: two hydrogens and one oxygen if I recall correctly. Dihydrogen monoxide.

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Let’s Talk Thickeners

While I’m re-thinking my approach to vanilla slices/custard squares, it strikes me that this is a good time to do a rundown of thickeners for the Baking Ingredients section. I’ve been asked several times to create one, but have never gotten around to it. Thickening is really the heart of my issue with vanilla squares, […]

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